Velocity responsive sensor for vehicle occupant restraints

ABSTRACT

A velocity responsive sensor operative upon impact engagement of a vehicle with an obstacle to sense the total change in vehicle velocity in a short deceleration time period and actuate the occupant restraint prior to the onset of significant deceleration of the occupant compartment of the vehicle if the change in vehicle velocity is greater than a predetermined value. The sensor includes upper and lower frames which open to each other and provide a housing. Each frame encloses and mounts a like sensor including an elongated planar spring arm having one end portion mounted to the frame and the other end portion slidably engaging an abutment surface lying in a vertical plane intersecting the vertical plane of the one end portion at an acute angle. A mass mounted on the other end portion moves horizontally into engagement with a compression spring contact when the free portion of the arm deflects horizontally relative to the one end portion of the arm. A stop for the free portion of the arm includes an arcuate rib on the frame tangentially related to the one end portion of the arm and wrappingly engaged by the arm adjacent such one end portion upon deflection of the free portion of the arm and engagement of the mass with the spring contact. The time period for the mass to change its energy and move into engagement with the spring contact is comparable to or greater than the deceleration time period of the vehicle. The mass and spring contact are connected across a source of power and an occupant restraint.

United states Patent [1.91 Orlando Nov. 27, 1973 VELOCITYRESPONSIVEJSENSOR FOR VEHICLE OCCUPANT RESTRAINTS Vincent A. Orlando,Clearwater, Fla.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

221 Filed: Sept. 25, 1972 21 Appl. No.: 292,085

[75] Inventor:

Primary Examiner-Kenneth l-l. Betts Assistant Examiner-Leslie J.Paperner Attorney-W. E. Finken et al.

[57] ABSTRACT A velocity responsive sensor operative upon impactengagement of a vehicle with an obstacle to sense the total change invehicle velocity in a short deceleration time period and actuate theoccupant restraint prior to the onset of significant deceleration of theoccupant compartment of the vehicle if the change in vehicle velocity isgreater than a predetermined value. The sensor includes upper and lowerframes which open to each other and provide a housing. Each frameencloses and mounts a like sensor including an elongated planar springarm having one end portion mounted to the frame and the other endportion slidably engaging an abutment surface lying in a vertical planeintersecting the vertical plane of the one end portion at an acuteangle. A mass mounted on the other end portion moves horizontally intoengagement with a compression spring contact when the free portion ofthe arm deflects horizontally relative to the one end portion of thearm. A stop for the free portion of the arm includes an arcuate rib onthe frame tangentially related to the one end portion of the arm andwrappinly engaged by the arm adjacent such one end portion upondeflection of the free portion of the arm and engagement of the masswith the spring contact. The time period for the mass to change itsenergy and move into engagement with the spring contact is comparable toor greater than the deceleration time period of the vehicle. The massand spring contact are connected across a source of power and anoccupant restraint.

3 Claims, 6 Drawing Figures VELOCITY RESTONSIVE SENSOR FOR VEHICLEOCCUPANT RESTRAINTS Thisinvention relates generally to velocityresponsive sensors for vehicle occupant restraint systems and moreparticularly tosuch sensors which sense the total change in vehiclevelocity in a short deceleration time period and actuate an occupantrestraint prior to the onset of significant deceleration of the occupantcompartment of the vehicle if the total change sensed is greater thanapredetermined value.

Inflatable occupant restraintsystems for vehicles are well known. Suchsystems include an inflatable occupant restraint cushion within theoccupant compartment of a vehicle. The cushion is inflated from apressure fluid source upon impact of the vehicle with an obstacle. Theimpact may be conventionally detected by an electrical contact switchmounted on the bumper and closed by the impact, various devices actuatedby a predetermined distance of movement of the bumper or the mountingstructure for the bumper, or one or more acceleration responsive sensorsmounted on vehicle body structure, such as the firewall or toe pan, andactuated when the sensor receives an acceleration pulse of predeterminedamplitude and time from such structure. Such sensors receive the pulsesafter the pulses have traveled through the body structure interveningbetween the point of impact and the sensor. If the pulse is not of therequired amplitude and time when it reaches the sensor, the sensor isnot actuated. Likewise, there is a time delay or interval between thetime of initial impact of the vehicle with an obstacle and the time'atwhich the pulse reaches the sensor.

Such time delay varies with the particular body structure on which thesensor is mounted, the intervening body structure, the presence ofenergy absorbing structure between the point of impact and theintervening body structure, as well as other factors. The sensors musttherefore be calibrated in accordance with the particular vehicle on,which they are to be used, the area of such vehicle on which they are tobe mounted, and damping of any impact generated pulses between theimpact point of origin and the sensor.

Acceleration responsive sensors may include a mass which is constrainedagainst movement from an unactuated to an actuated position by springsor magnets which apply a preload force to the mass. Generally thepreload force is quite high in order that the sensor be calibrated andthat the mass not inadvertently move to an actuated position undernormal driving conditions or under certain abnormal driving conditionswhich do not involve impact of the vehicle with an obstacle or doinvolve such an impact but at a level at which it is not necessary toinflate the cushion. The distance of movement of the mass to actuatedposition is usually relatively short, such as V: inch, and the preloadforce applied to the mass is quite high.

The sensor of this invention includes upper and lower frames ofdielectric material, each of which encloses and mounts a like sensor.The frames open to each other and provide a housing for the redundantsensors. Each frame is generally of triangular shape and includes a basewall and a continuous side wall. Planar mounting and abutment surfacesare spaced from each other 'on a leg of the side wall and lie in planesintersecting each other at an acute angle. An elongated planar leafspring member has one end portion seating on the mounting surface andsecured to the housing. The

- other end portion of the'spring member mounts a mass and slidablyengages the abutment surfaceto deflect the free portion of the springmember from its normal undeflected position. The acute angle is in theorder of 8, 4 of which provide a preload force and 4 of which ensureuniformity of response time for the mass for impacts directed 30 toeither side of a perpendicular to the abutment surface. A columnardeflectable contact spring is mounted on another leg of the side walland is deflectably engaged by the mass upon deflection of the freeportion of the spring member and actuation of the sensor. The contactspring and the mass are connected across both diagnostic and actuatingcircuits. The housing further includes a rib extending between thecontact spring mounting and the planar mounting surface and having anarcuate portion tangentially related to the mounting surface andwrappingly engaged by the free portion of the spring member upondeflection thereof to control such deflection and prevent overstressingof the free portion when the mass moves into engagement with the springcontact.

The sensor is mounted on the bumper or any other portion of the vehiclewhich experiences a rapid change in velocity upon impactof the vehiclewith an obstacle. The sensor may also be mounted remote from the bumperor such portion of the vehicle and connected thereto so as to besimultaneously subjected to any changes in velocity experienced thereby.

In front end impacts, the bumper of the vehicle is ordinarilythe firstpart of the vehicle which contacts the obstacle and likewise the firstpart of the vehicle which comes to a complete rest while the remainderof the vehicle is still decelerating. Actual tests have shown that aninterval of 3 to 8 ms occurs between the time of initial bumper contactwith an obstacle and the time that movement of the bumper ceases, in animpact of a 28 to 30 mph barrier equivalent. Thus, substantially thetotal change in velocity of the bumper occurs prior to the total changein velocity of the occupant compactment and prior to the onset of anysignificant deceleration of the occupant compartment. The sensor issubjected to this same total velocity change simultaneously with thebumper and initiates actuation of an occupant restraint within theoccupant compartment prior to any significant deceleration of thecompartment when the sensor detects the occurrence of a change invehicle velocity above a predetermined value.

The spring and mass of the sensor have a period of natural frequencywhich is comparable to or greater than the deceleration time period ofthe bumper or other portion of the vehicle on which the sensor ismounted. The period of natural frequency is set in accordance with thedesired change in velocity and the. time period of such change whichmust occur before the sensor initiates actuation of the occupantrestraint. The movement of the mass to actuated position is thereforeprimarily responsive to a change in velocity of the portion of thevehicle on which the sensor is mounted occurring within a certain timeperiod. It is not due primarily to the receipt by the sensor of anacceleration pulse generated by impact. While an instantaneous change invelocity of any portion of the vehicle is unobtainable, in other words,it is impossible to instantaneously stop any portion of the vehicle uponimpact with an obstacle, the change in velocity of the bumper or otherportion of the vehicle on'which the The sensor is relatively insensitiveto the body structure of the particular vehicle and the response time isrelatively fast since there is no time delay. or. interval between anygeneration of an acceleration pulse and receipt of such pulse by thesensor.

One of the features of the sensor of this invention is t that itincludes an elongated spring arm secured at one end portion to a vehiclemounted support and mounting a mass at the other end portion thereof,the free portion of the spring arm being'deflectable relative to thesupport upon impact of the vehicle with an obstacle and the occurrenceof apredetermined change in vehicle velocity in a short decelerationtime period to move the mass into engagement with a contact and actuatea vehicle occupant restraint, the time period for the mass to change itsenergy and move into engagement with the contact being comparable to orgreater than the deceleration time period of the vehicle. Anotherfeature is that the deflection of the free portion of the spring arm iscontrolled by an arcuate stop surface tangentially related to the freeportion of the spring arm and. wrappingly engaged thereby adjacent itssecured end portion. A further feature is that the contact includes acolumnar spring which deflects relative to its mounting on the supportwhen engaged by the mass. Yet another feature is that the support is agenerally triangularlyshaped housing, the spring arm being located atone side of the housing, and the spring contact and arcuate stop surfacebeing located at the other side of the housing. Yet a further feature isthat the housing is of dielectric material and includes planar mountingand abutment surfaces respectively seating the one and the otherendportions of the spring arm, the surfaces lying in vertical planesintersecting each other at a predetermined acute angle. Still anotherfeature is that the columnar spring is mounted on a third planar surfaceangularly related to the mounting and abutment surface, the arcuate stopmeans being provided by a rib connecting the third planar surface andthe mounting surface and tangent to the latter. Still a further featureis that the rib spans the other side of the housing.

These and other features of the sensor of this invention will be readilyapparent from the following specification and drawings wherein:

FIG. 1 is a perspective view of a portion of a vehicle having a sensoraccording to this invention for actuating an occupant restraint of theinflatable cushion type;

FIG. 2 is an enlarged view taken generally along the plane indicated byline 2-2 of FIG. 1;

FIG. 3 is a sectional view taken generally along the plane indicatedbyline 3-3 of FIG. 2;

FIG. 4 is a sectional view taken generally along the plane indicated byline 44 of FIG. 2;

FIG. 5 is a sectional view taken generally along the plane indicated byline 5-5 of FIG. 2; and

FIG. 6 is a sectional view taken generally along the plane indicated byline 6-6 of FIG. 2.

Referring now particularly to FIG. 1 of the drawings, a vehicledesignated generally 10 includes a frame 12 having a pair of frame rails14 connected adjacent their forward ends by a cross frame member16'providing a support for the vehicle power plant, not shown. A likepair of energy absorbing struts 18, respectively mounted on the rails 14at their forward ends, mount the vehicle bumper 20. A sensor 22according to this invention is mounted on the bumper 20 and actuates agas generator 24 of the occupant restraint system 26 of the vehicle.When the gas generator is actuated, it supplies pressure fluid toinflate an inflatable occupant restraint cushion 28 which is mountedwithin the occupant compartment 300f the vehicle. The occupant restraintsystem 26, including the gas generator, the cushion, and the connectingmanifold and diffuser structure is conventional and well known to thoseskilled in the art. Accordingly, it is not believed that any furtherdescription need be given.

Referring now to- FIGS. 2 through 6 of the drawings, the sensor 22includes upper and lower open frames 32 and 34, respectively, of likeasymmetrical shape and molded of dielectric material. Each frame housesa sensor of like construction and, accordingly, only the lower frame andsensor will be described in detail. It will be understood that the upperframe and sensor are of like construction, unless otherwise noted, andthat like parts thereof will be indicated by prime numerals.

The frame 34, as shown in FIG. 2, is generally of triangular shape andincludes a base wall 36 and a continuous peripheral wall 38. As bestshown in FIGS. 3 through 6, the upper edge of wall 38 includes acontinuous peripheral shoulder 40 which receives a continuous peripheralrib 42 on the lower edge of wall 38' so that the edges interfit and theframes 32 and 34 close each other to provide an enclosure or housing forthe redundant sensors contained therein- The interfltting edgesareadhesively secured toeach other.

A number of rivets 44, extending through aligned openings in walls 38and 38', further secure the frames 32 and 34 to each other and to a baseplate 46 of a mounting bracket assembly. The assembly includes an uppercover 48 of a cross sectional shape as shown in FIG. 2 and having aperipheral flange 50 which is riveted at 52, FIG. 2, to plate 46. Thecover 48 is larger in size than the frames 32 and 34, as can be seenfrom FIG. 2, and the space therebetween is filled with any suitablesealant 54, such as lithium grease, as indicated.

As shown in FIG. 2, the peripheral wall 38 of housing 34 includes avertical abutment surface 56 formed integrally therewith and facingforwardly of the vehicle as will be explained. Spaced from this abutmentsurface is a-vertical slot 58, FIG. 5, formed in an enlargement of wall38. The surface 56 and the walls of slot 58 lie in vertical planesintersecting each other at a predetermined included acute angle. In thespecific embodiment shown, this angle is 8 and will be furtherexplained. A leaf spring arm or member 60 of predetermined elasticcharacteristics has a mass 62 secured to one end portion thereof. Theother end portion of the arm seats on one wall or planar mountingsurface of slot 58, FIG. 5, and includes an integral return bent flange64 seating on the other wall to wedgingly mount the spring arm to wall38. An integral lateral flange 66 of the spring arm is received in arecess of the enlargement of wall 38 and secured thereto by a screw 68threaded into an opening of the enlargement. Since the planar surface 56and planar mounting surface of slot 58 are located at an acute angle,shown as 8, relative to each other, the free portion of the spring arm60 is slightly deflected from its normal undeflected position asshown inFIG. 2. 4 of this angle provides a preload force normally locating thespring armand the mass 62 in their unactuated position'as shown in FIG.2, and 4 ensures uniformity of response time for the mass for impacts.of the bumper directed 30 to either side of a perpendicular to theabutment surface 56.

A conductor 70 is received within an integral groove 72 of wall'38 andincludes an extension 74 at one end and an angular extension 76 at theother end. As shown in FIG. 5, the extension 74 overlies the flange 64of spring arm 60 and is secured to the recess of the enlargement of wall38 by the same screw 68. The angular extension 76, as shown in FIG. 6,is welded to a contact post 78 which is molded within the wall 38 andextends therethrough.

Another conductor 80 is likewise received within an integral groove ofwall 38 and includes an angular extension 82 at one end thereof andanother angular extension 84 at the other end thereof. Extension 82 iswelded-to a contact post 86, FIG. 2, molded within wall 38 in the samemanner as contact post 78. The contact posts are connected across a 600ohm resistor 88.

A contact 90 in the form of a columnar coil spring is mounted on theflange 92 of extension 84 as best shown in FIG. 4. Integral tabs 94 arestruck out of the flange 92 and are then bent over the lowermost-coil ofthe contact 90 to secure the contact to the extension. The extension 84is further secured in place within the groove of the wall 38 by a screw96.

As best shown in FIG. 2, an integral rib 98 of frame 34 extendsgenerally vertically with respect to the base wall 36 of the frame. Therib 98 extends between the enlargement of wall 38 containing slot 58 andthe enlargement100 of the wall 38 which contains the integral groovereceiving conductor 80 and the flange 84 thereof. The rib 98 isgenerally linear except for the arcuate vertical surface portion 102thereof which merges tangentially into the wall of slot 58 against whichthe spring member 60 seats as shown in FIG. 5. The rib 98 provides astop surface for the spring member 60, and particularly, the surfaceportion 102 thereof is wrappingly engaged by the spring member 60 whenthis member deflects to actuated position .as shown in dash lines inFIG. 2 to limit the deflection of the spring member and prevent anyoverbending or stress thereof.

From the foregoing description, it can be seen that the frame 34including its mounting and abutment surfaces provided by the slot 58 andthe surface 56, respectively, as well as the grooves which receive theconductors 70 and 80 and the rib 98, is of integrally molded one-piececonstruction.

An angle bracket 104 welded to plate 46, FIG. 2, supports a lead 106. Acoaxial type wiring harness 108 extends through the lead 106 and theninto the cover 48 wherein itis connected to the contact posts 78 and 86of each of the frames 32 and 34. The harness 108 is grounded to theplate 46 in a known manner.

The sensor 22 is essentially comprised of two like sensors which arecalibrated to the same constants so that both will be actuated when thebumper of the vehicle experiences a velocity change of predeterminedvalue. The sensor 22is fixedly secured to the bumper 20 by a number ofbolts, not shown, which extend through aligned openings 110 in theflange 50 of cover 48 and also in plate 46 and through like openings ina series of brackets 112 which are secured in a known manner to thebumper 20, such as to the upper wall thereof as shown in FIG. 1. By thusfixedly securing the sensor 22 to the bumper 20, the changes in velocityexperienced by the bumper 20 are likewise experienced by the sensor 22.It might-also be noted at this point that the sensor 22 is mounted tothe bumper 20 in a horizontal position with the surface 56 facingforwardly of the vehicle so that the spring member 60 and mass 62 arepositioned generally vertically but face horizontally.

When the bumper 20 experiences a change in velocity of predeterminedvalue, both spring members 60 and 60' as well as their respective masses62 and 62 move horizontally forwardly of the bumper 20 to each closeagainst the respective other contacts provided by the respective springs90 and 90. Thus, action of each will be generally simultaneously. Whenthe respective masses close against their respective springs, thesprings can deflect axially under the like columnar loads applied by themasses 62 as they engage the springs, and likewise the springs candeflect about their lowermost mounted coil as required. When therespective masses 62 close to the respective contacts 90 and 90,respective circuits are completed across the spring members 60 and thesprings 90 and 90'. One lead of the wiring harness 108 is connected tothe post 78 and thence by the conductor to the spring arm 60, whileanother lead of the harness 108 is connected to the post 86 and to thespring by the conductor 80, with the posts being connected across theresistor 88 as previously mentioned. Other leads'of the harness 108 arelikewise connected to posts 78' and 86'.

As schematically shown in FIG. 1, the wiring harness 108 interconnectsthe sensor 22 and the gas generator 24 of the occupant restraint system26. Although not shown herein since it is not necessary to anunderstanding of this invention, it will be understood that the wiringharness 108 is part of an actuation circuit which includes the vehiclebattery which furnishes power for firing the gas generator 24 to inflatethe cushion 28 when the sensors which form the sensor 22 are bothactuated. A suitable actuation circuit is known to those skilled in theart. For such a circuit which additionally includes backup andmonitoring, reference may be had to Ser. No. 190,978 Dillman et al,filed Oct. 20, 1971 and assigned to the assignee of this invention. Insuch disclosure, the sensors which form the sensor 22 will comprise theswitches 10a and 10b.

As has been previously stated, the sensor is mounted on a portion of thevehicle which comes to rest in a time period which is short compared tothe decelerating time of the occupant compartment. In such a location,it has been shown that the amplitude of the deceleration pulse is not areliable indication of crash severity-crash severity being a measure ofinjury-to the vehicle occupant. It is only by making the sensorresponsive primarily to velocity that discrimination of crash intensitycan be made as will be demonstrated later. The velocity sensitive natureof this sensor is based on the concept of a simple mass supported on asimple spring. If an impulse, an instantaneous change in velocity, V,,,is imparted to the mass, the maximum excursion of the mass, S andmaximum acceleration of the mass, A,,, are given by thewell-knownrelationships describing a steady state, undamped oscillation:

V, S W

- A V,,W

The value of W is given by the well-known relationship W V K/M, where Kis the elastic constant of the spring and M is the mass supported on thespring (and in this case, it includes not only the supported mass, butalso the total mass of the restraining springs). The selection of W isbasic to this invention as will be shown by a table of values. lmpulseswhich are comparable to or shorter than the natural period of the'springmass arrangement introduce only that amount of error in the measurementof true velocity which is desirable and necessary in a sensor. If thesensor responded perfectly to a change ln velocity, it would actuatewhenever a predetermined change in velocity of the vehicle occurred,such as that due to normal vehicle braking. This is clearly undesirable.It can be further shown that for a hard crash, such as a crash into arigid barrier, actuation should occur at a lower speed and in a fastertime than in a soft crash, such as into the side of another vehicle. Itis a feature of this invention that by a proper combination of resonantfrequency, mass distance to the contacts, and location and orientationof the sensor, the sensor can be designed to actuate under differentcrash conditions in different times and different velocities so that ineach case it can subject the occupant of the vehicle to an impactseverity which is approximately equal in spite of the large variationsin impact conditions.

A quantitative measure of crash severity can be as-.

signed by describing the shape and time duration of the accelerationpulse for a given velocity change. Experience has shown that a hard orbarrier crash is often represented by a damped sine wave of a period ofosciliqn off? o smilliseconds A sQ t sresbsanbs represented by ahaversine. Experience has shown that most crashes have a decelerationpulse that lies somewhere between the damped sine wave and a haversine.The calculated values of threshold velocity and actuation times of aparticular sensor experiencing these two inputs for various input timeconstants, r, are presented in the following table which shows thefiring times for various pulse periods for a sensor calibrated to fireat a change in velocity of 11 mph.

11 m.p.h. SENSOR RESPONSE V 21r 10 18- 1-cos t) A l A=acceleration in GeV= velocity in inches/sec. -r-- TIME 1 and t in seconds Equation for adamped sine wave:

1.26 T A, A A=1.69 10"e sin ;t

l5 :T I

It is instructive to note that certain low speed crashes have highervalues of acceleration than some high speed crashes. Since the sensorhas no way of knowing the kind of crash that it will be involved in, itsresponse must not be acceleration dependent, but rather primarilyvelocity dependent as already stated. For example with a damped sinewave input having a time constant, T, of 2 ms, the threshold value ofthe sensor (the value below which the sensor will not actuate) is 10.6mph and the peak G value experienced by the sensor is 1580. The time forthe sensor to fire after initiation of the pulse is 13.5 ms. Clearly,the sensor is primarily responsive to velocity.

The A values in the table may be compared with similar values of anacceleration responsive sensor. In such a sensor, A, would beapproximately equal to 150s. While both sensors use what may be termedspring mass systems, it can be seen that the spring mass system of thesubject sensor is relatively immune to acceleration pulses and isresponsive only to a predetermined change in vehicle velocity in apredetermined time period while the acceleration responsive sensor is Iresponsive only to acceleration pulses of much lower pulse reaching itthrough any intervening body struc- Input acceleration pulsecharacteristics Haversine Damped sine Pulse Velocity Fire Peak VelocityFire Peak period fire time fire time G Impact velocity (m s m.p.h. m.sA0 m.p.h. m.s. A

Threshold velocity (nominally 11 m.p.h.) 30

The parameters of the sensor on which the table is cushion.

ture. The sensor 22 can receive impact information and actuate thecushion before the occupant or the occupant compartment has experiencedany significant deceleration and before an acceleration responsivesensor could receive the same information and actuate the To summarize,the sensor 22 of the system of this invention includes a mass having aperiod of natural frequency which is comparable to or larger than thedeceleration time period of the bumper or other portion of the vehicleon which the sensor is mounted and which is subjected to impact forcesso as to experience a total change in velocity before the occupantcompartment experiences such total change or experiences any significantdeceleration. While the sensor 22 may be mounted on the bumper or otherportion of the vehicle, it may also be mounted remote from the bumper orportion of the vehicle and rigidly connected thereto, such as by stiffrods, such that the sensor 22 experiences the same deceleration withinthe same time period as the bumper or other portion of the vehicle.

It should also be noted that the sensor 22 shown herein has directionalsensitivity in that it is responsive to horizontal pulses receivedwithin the included angle of to either side of a perpendicular tosurface 56.

While a specific example of a sensor has been disclosed herein, one setto fire at a change in velocity of 11 mph within a certain time period,the sensor, of course, can be set to fire at other changes in velocitieswithin similar time periods.

Thus, this invention provides an improved velocity responsive sensor forvehicle occupant restraints.

I claim:

, 1. In combination with a vehicle including an occupant compartment andan occupant restraint, a velocity responsive sensor operative uponimpact engagement of the vehicle with an obstacle to sense the totalchange in vehicle velocity in, a short deceleration time period prior tothe onset of significant deceleration of the occupant compartment andactuate the occupant restraint, comprising, a housing mounted on thevehicle and including spacedmounting means and abutment means lying inplanes intersecting each other at a predetermined included acute angle,an elongated spring member having one end portion thereof secured to themounting means, the other end portion of the spring member seating onthe abutment means to deflect the free portion of the spring member fromnormal undeflected position, a mass secured to the other end portion ofthe spring member, contact means mounted on the housing in spacedrelationship to the abutment means and engageable by the mass upondeflection of the free portion of the spring member relative to thesecured end portion thereof, the time period for the mass to change itsenergy and move into engagement with the contact means being comparableto or greater than the deceleration time period of the vehicle wherebyengagement of the mass with the contact means is responsive to theoccurrence of a change in vehicle velocity greater than a predeterminedvalue, means on the housing tangential to the one secured end portion ofthe spring member and wrappingly engaged by the free portion of thespring member adjacent the one secured end portion thereof upon movementof the mass into engagement with the contact means to thereby limit andcontrol the deflection of the free portion of the spring member, andcircuit means connecting the spring member and the contact means acrossa source of power and the occupant restraint, movement of the mass intoengagement with the contact means actuating the occupant restraint whenthe housing is subjected to substantially the total change in velocityof the vehicle in a short deceleration time period prior to the onset ofsignificant deceleration of the occupant compartment of the vehicle.

2. In combination with a vehicle including an occupant compartment andan occupant restraint, a velocity responsive sensor operative uponimpact engagement of the vehicle with an obstacle to sense the totalchange in vehicle velocity in a short deceleration time period prior tothe onset of significant deceleration of the occupant compartment of thevehicle and actuate the occupant restraint, comprising, a housingmounted on the vehicle and including spaced planar mounting and abutmentsurfaces lying in planes intersecting each other at a predeterminedincluded acute angle. an elongated planar spring member having one endportion thereof seating on the mounting surface, means securing the oneend portion of the spring member to the housing, the other end portionof the spring member seating on the abutment surface to deflect the freeportion of the spring member from normal undeflected position, a masssecured to the other end portion of the spring member, contact meansmounted on the housing in spaced relationship to the abutment surfaceand engageable by the mass upon deflection of the free portion of thespring member relative to the one end portion thereof, the time periodfor the mass to change its energy and move into engagement with thecontact means being comparable to or greater than the deceleration timeperiod of the vehicle whereby engagement of the mass with the contactmeans is responsive to the occurrence of a change in vehicle velocitygreater than a predetermined value, arcuate rib means on the housingtangential to the mounting surface and wrappingly engaged by the freeportion of the spring member adjacent the one end portion thereof uponmovement of the mass into engagement with the contact means to therebylimit and control the deflection of the free portion of the springmember, and circuit means connecting the spring member and the contactmeans across a source of power and the occupant restraint, movement ofthe mass into engagement with the contact means actuating the occupantrestraint when the housing is subjected to substantially the totalchange in velocity of the vehicle in a short deceleration time periodprior to the onset of significant deceleration of the occupantcompartment of the vehicle.

3. In combination with a vehicle including an occupant compartment andan occupant restraint, a velocity responsive sensor operative uponimpact engagement of the vehicle with an obstacle to sense the totalchange in vehicle velocity in a short deceleration time period prior tothe onset of significant deceleration of the occupant compartment of thevehicle and actuating the occupant restraint, comprising, a housingmounted on the vehicle and including spaced planar mounting and abutmentsurfaces lying in planes intersecting each other at a predeterminedincluded acute angle, an elongated planar spring member having one endportion thereof seating on the mounting surface, means securing the oneend portion of the spring member to the housing, the other end portionof the spring member seating on the abutment surface to deflect the freeportion of the spring member from normal undeflected position, a masssecured to the other end portion of the spring member, a columnarcontact spring mounted on the housing in spaced relationship to theabutment surface and engageable by the mass upon deflection of the freeportion of the spring member relative to the one end portion thereof,the time period for the mass to change its energy and move intoengagement with the contact spring being comparable to or greater thanthe deceleration time period of the vehicle whereby engagement of themass with the contact spring is responsive to the occurrence of a changein vehicle velocity connecting the spring member and the contact springacross a source of power and the occupant restraint, movement of themass into engagement with the "contact spring actuating the occupantrestraint when the housing is subjected to substantially the totalchange in velocity of the vehicle in a short deceleration time periodprior to the onset of significant deceleration of the occupantcompartment of the vehicle.

1. In combination with a vehicle including an occupant compartment andan occupant restraint, a velocity responsive sensor operative uponimpact engagement of the vehicle with an obstacle to sense the totalchange in vehicle velocity in a short deceleration time period prior tothe onset of significant deceleration of the occupant compartment andactuate the occupant restraint, comprising, a housing mounted on thevehicle and including spaced mounting means and abutment means lying inplanes intersecting each other at a predetermined included acute angle,an elongated spring member having one end portion thereof secured to themounting means, the other end portion of the spring member seating onthe abutment means to deflect the free portion of the spring member fromnormal undeflected position, a mass secured to the other end portion ofthe spring member, contact means mounted on the housing in spacedrelationship to the abutment means and engageable by the mass upondeflection of the free portion of the spring member relative to thesecured end portion thereof, the time period for the mass to change itsenergy and move into engagement with the contact means being comparableto or greater than the deceleration time period of the vehicle wherebyengagement of the mass with the contact means is responsive to theoccurrence of a change in vehicle velocity greater than a predeterminedvalue, means on the housing tangential to the one secured end portion ofthe spring member and wrappingly engaged by the free portion of thespring member adjacent the one secured end portion thereof upon movementof the mass into engagement with the contact means to thereby limit andcontrol the deflection of the free portion of the spring member, andcircuit means connecting the spring member and the contact means acrossa source of power and the occupant restraint, movement of the mass intoengagement with the contact means actuating the occupant restraint whenthe housing is subjected to substantially the total change in velocityof the vehicle in a short deceleration time period prior to the onset ofsignificant deceleration of the occupant compartment of the vehicle. 2.In combination with a vehicle including an Occupant compartment and anoccupant restraint, a velocity responsive sensor operative upon impactengagement of the vehicle with an obstacle to sense the total change invehicle velocity in a short deceleration time period prior to the onsetof significant deceleration of the occupant compartment of the vehicleand actuate the occupant restraint, comprising, a housing mounted on thevehicle and including spaced planar mounting and abutment surfaces lyingin planes intersecting each other at a predetermined included acuteangle, an elongated planar spring member having one end portion thereofseating on the mounting surface, means securing the one end portion ofthe spring member to the housing, the other end portion of the springmember seating on the abutment surface to deflect the free portion ofthe spring member from normal undeflected position, a mass secured tothe other end portion of the spring member, contact means mounted on thehousing in spaced relationship to the abutment surface and engageable bythe mass upon deflection of the free portion of the spring memberrelative to the one end portion thereof, the time period for the mass tochange its energy and move into engagement with the contact means beingcomparable to or greater than the deceleration time period of thevehicle whereby engagement of the mass with the contact means isresponsive to the occurrence of a change in vehicle velocity greaterthan a predetermined value, arcuate rib means on the housing tangentialto the mounting surface and wrappingly engaged by the free portion ofthe spring member adjacent the one end portion thereof upon movement ofthe mass into engagement with the contact means to thereby limit andcontrol the deflection of the free portion of the spring member, andcircuit means connecting the spring member and the contact means acrossa source of power and the occupant restraint, movement of the mass intoengagement with the contact means actuating the occupant restraint whenthe housing is subjected to substantially the total change in velocityof the vehicle in a short deceleration time period prior to the onset ofsignificant deceleration of the occupant compartment of the vehicle. 3.In combination with a vehicle including an occupant compartment and anoccupant restraint, a velocity responsive sensor operative upon impactengagement of the vehicle with an obstacle to sense the total change invehicle velocity in a short deceleration time period prior to the onsetof significant deceleration of the occupant compartment of the vehicleand actuating the occupant restraint, comprising, a housing mounted onthe vehicle and including spaced planar mounting and abutment surfaceslying in planes intersecting each other at a predetermined includedacute angle, an elongated planar spring member having one end portionthereof seating on the mounting surface, means securing the one endportion of the spring member to the housing, the other end portion ofthe spring member seating on the abutment surface to deflect the freeportion of the spring member from normal undeflected position, a masssecured to the other end portion of the spring member, a columnarcontact spring mounted on the housing in spaced relationship to theabutment surface and engageable by the mass upon deflection of the freeportion of the spring member relative to the one end portion thereof,the time period for the mass to change its energy and move intoengagement with the contact spring being comparable to or greater thanthe deceleration time period of the vehicle whereby engagement of themass with the contact spring is responsive to the occurrence of a changein vehicle velocity greater than a predetermined value, spring memberstop means on the housing including an arcuate surface tangentiallyrelated to the mounting surface and wrappingly engaged by the freeportion of the spring member adjacent the one end portion thereof uponmovement of the mass into engagement with the contact spring to therebylimit and contRol the deflection of the free portion of the springmember, and circuit means connecting the spring member and the contactspring across a source of power and the occupant restraint, movement ofthe mass into engagement with the contact spring actuating the occupantrestraint when the housing is subjected to substantially the totalchange in velocity of the vehicle in a short deceleration time periodprior to the onset of significant deceleration of the occupantcompartment of the vehicle.